Method of decarbonizing oil refining apparatus



w. T. DAVIS 1,901,803

METHOD OF DECARBONIZING OIL REFINING APPARATUS I March 14, 1933.

Filed July 1, 1930 INVENTOR:

ATTORNEYS Patented Man, 1933 PATENT orrlca UNITED s'r 'ras Application and m 1, 1930. Serial no. team.

This invention relates to a method of decarbonizing oil refining apparatus such for example as the tubular type of oil stills. These stills are usually made of lengths of ipe united at the ends by so-called junction oxes, return bends or headers. The oil is caused to flow through the tubes, While heat is applied to the outside thereof. The oil in the tubes, either in liquid or vapor phase, becomes heated. During this process a coating of so-called petroleum coke becomes deposited on the interior of the still and appurtenances thereof. This necessitates the shutting down of the still at frequent. periods since the coke is a poor con-.-

ductor of heat and also because the coke clogs the tubes, rendering the passage of the liquid and vapors therethrough diflicult. Heretofore, it has been the practice to remove the coke from the interior of the apparatus by one of two methods, the first consisting. of mechanical removal by scraping or chipping, the second consisting of burning with a torch usin industrial fuel gas and compressed air. .oth methods had serious objections, the first was slow and required expensive apparatus; the second involving dan er of damage of the .walls to the apparatus y the heat of the burning coke. 7

An object of my invention is to provide a method whereby the coke may be removed rapidly and inexpensively and without danger to the refining apparatus. Upon experimenting with the removal of the coke with 5 oxygen I have found, much to my surprise,

that although oxygen produces a higher temperature, it is possible to remove the coke by burning in the presence of oxygen or air enriched in. oxygen without injury to the walls of the'apparatus.

My preferred method of removing coke from the interior of an oil refining apparatus consists in burning it out in the presence of substantially pure oxygen. While I may do this in various difi'erent ways and with various types of apparatus I prefer to use a torch providing a preheating flame and a blast or jet of substantially pure oxygen. I may, of

course, use separate torches should I so desire. The pre-heating flame is preferably an inch in thickness, and a hole is rapidly oxy-acetylene flame, containing. oxygen and acetylene in the proportions to give-whatis known as a neutral welding flame, although of course other proportions may be employed. While I might use other fuelgases, such as illuminating gas, I prefer to use acetylene, since I find this most satisfactory. I have also found that carbon dioxide, which is formed during the burning of the coke, reacts with the heatedcokeadjacent G3 thereto forming carbon monoxide, thus resulting in an economy of oxygen. The jet and pre-heating flame are directed against the layer of coke, which often-is as much as C5 burned to the wall of the still; The oxygen then apparently extends sideward, in a mushroom shaped formation, eating away the 1m- 'der part of the coke,

may be called under urning. This burns 'ving an efi'ect which 7 Q the coke away from the tube wall very rapidly in the presence of theoxygen atmosphere and there is no time to heat the 'walls I of the still to suchan extent thatthere is any possibility of injury thereto. Should the re- '75 maining portion of the coke burn it will be spaced from the still wall, and there will be no heat conduction to the wall. As amat-' ter of fact, however, not all of the remaining coke is burned in place. Duezto the underburning, together with differential expansion in portions of the coke, e ansionsof the, products of combustion, or t e force of. the oxygen jet, large portions of the coke be come detached and are either broken away or fall under influence of gravity. In order to strengthen this effect the oxy en is under comparatively high pressures ing delivered to the torch at pressure as high as one hundred 'lbs. per square inch.

Before starting upon the operation of burning out the coke the oil refimng apparatus is purged out by circulating steam or some neutral gas therethrough." a

While I have discussed the use of my process as applied to oil still tubes and return bonds it is to be understood that I include 'any parts of oil refining apparatus in which the so-called coke is deposited.

I am aware that it is old in'the art to remove the so-called carbon from the cylinders of the internal combustion engines by burning in the presence of oxygen. My process differs from this in several important respects. Amongthese may be mentioned the material which is removed. The so-called carbon in automobile c linders consists in a mixture of road dust, ubricating oil residues,-and carbon resulting from imperfect combustion of the gasoline. The road dust may run as high. as Thus it will evident that the material to be acted upon is quite different. The so-called carbon buming is merely a burnin of the residues of the lubricating oil and uel mixture, resulting in a disintegration and a freeing of the road dust. Moreover, due to the fact that the automobile cylinder is almost completely enclosed, it is possible to fill the interior of the cylinder with oxygen. With oil refining apparatus this is rarely possible and, when possible, would involve a large waste of oxygen. Moreover, in internal combustion engines the carbon deposit is so thin and so diluted with inert matter that it may be completely burned before the cylinder wall is heated to a temperature above that which is found during the operation of the engine. For this reason it is unnecessary to provide the precautions against heating, which I have disclosed. Although it isnot absolutely essential that the pro-heating flame be used during my entire process, I have found it more advantageous and prefer to use it, while in burning carbon from the interior of internal combustion engines the carbon once ignited burns without the use of a pre-heating flame. In my method the oxygen is directed against the coke deposit, preferably at the base, at high velocities, while in the old process this is not done.

The method of my invention is illustrated inthe drawing, in which Figure 1 re resents a suitable torch for decarbonizing and Figure 2 illustrates diagrammatically my method of applying the torch.

In Figure 1 an oxygen nozzle 10 is shown in convenient juxtaposition to the heating flame nozzle-11. The flow of oxygen under high pressure through the nozzle 10 is controlled by a suitable valve arrangement 12. The flow of combustible gas for the heating flame is controlled by a valve 13, and the neocessary oxygen for the heating flame is bled from the oxygen line into the stream of combustible gas through the control valve 14. The nozzles 10 and 11 and their supply tubes may be changed if desired by disconnecting them at the junction 15.

The method of using the above torch may be seen in Figure 2, wherein the preheating flame from the nozzle 10 raises a portion of the deposit 16 to its ignition temperature in oxygen, whereuponthe stream of high-pressure oxygen from the nozzle 11 burns rapidly throughthe deposit 16 to the metal surface 17 undercuts the deposit 16, burns the undersi e of said deposit out of contact with the metal surface 17 and loosens and separates appreciable portions of the deposit 16 from said metal surface without completely consuming the material of the deposit.

I claim:

1. Method of :lecarbonizing the interior of an oil refining ap aratus which comprises i dues from the interior of an oil refining apparatus which comprises heating the cokelike residue with anoxy-acetylene flame and supplying an atmosphere of substantially pure oxygen to said heated residue and maintaining said heating flame during the removal of the residue, whereby the time during which any given portion of said apparatus is heated is substantially reduced.

3. Method of removing a coke-like residue from the interior of an oil refining apparatus which comprises purging the still with a noncombustible fluid, heating the residue and supplying the heated residue with an atmosphere richer in oxygen than air, said atmosphere being supplied at ahigh velocity and in such a manner that it detaches pieces of unburned residue from the walls of the apparatus.

In testimony whereof, I aflix my signature.

' WILLIAM T. DAVIS. 

